1. Field of the Invention
The present invention relates generally to articles of footwear, and more specifically to articles of footwear adapted to slide over elongated support surfaces.
2. Description of the Prior Art
One activity enjoyed primarily by today's youth is using in-line skates or skateboards to drive the metallic or wooden bottom surface of such equipment onto curbs, rails, or other manmade obstacles to slide therealong. The popularity of this activity, commonly referred to as "grinding", along with the burden of carrying or wearing such equipment led to the advance described in U.S. Pat. No. 6,006,451, assigned to the present applicant. Such patent generally describes athletic shoes incorporating a plate for performing similar and novel sliding maneuvers over rigid support surfaces commonly found in outdoor settings such as parking lots and walkways as well as obstacles provided in manmade skate parks. These shoes, sold under the brand name SOAP.RTM., enable normal walking and running functions while incorporating a plate recessed upwardly from the bottom surface of the shoe sole for grinding along the rigid support surfaces as encountered on pipe railings, curb edges, and similar obstacles.
While this device has enjoyed considerable commercial success, athletes of all skill levels continue to insist on additional features such as grind plates with replaceable wear sections or variable frictional characteristics for riding on different surfaces or for different working areas of the plate to assist in speed control, especially over steeply inclined surfaces. Applicant's assignee has developed three separate approaches to such variable customer demand. One particular effort is described in U.S. Pat. No. 5,970,631. Disclosed is a grinding shoe apparatus which includes a grind plate carried from a backing plate embedded in the sole of a shoe. The grind plate includes a plurality of bores receiving movable grind elements formed with downwardly facing grind surfaces which may have different coefficients of friction. While such device is considered satisfactory for many grinding maneuvers, placement of additional frictional surfaces is desirable in other locations such as on the lateral sides of the plate where many grinders prefer to slide.
Another effort is described in U.S. Pat. No. 6,006,450, also owned by applicant. This device incorporates a wear resistant brake tab secured between the upper and the plate and having an abrasive surface to enable the grinder to roll over the shoe and contact the rail to slow down the speed of the slide. This device is primarily for protecting the upper against excessive wear and may require a significant amount of rolling prior to engagement with the support surface to provide a braking function.
A third effort found in U.S. Ser. No. 09/364,756, also assigned to applicant, is a grinding plate bonded to the shoe sole and including laterally spaced apart bearing surfaces positioned adjacent elevated braking surfaces that provide the desired speed control. Such braking surfaces incur a lot of wear and, when sufficiently worn, must be replaced along with the entire plate which may result in useful non-bearing surface material being discarded.
It has been found that select portions of the grinding plate where preferred sliding and braking occurs may incorporate removable inserts which have variable frictional characteristics to provide alternative speed control features and facilitate replacement of worn surfaces thereby avoiding replacement of the entire plate. It is those features to which the present invention is directed.